The present invention relates to excavation devices. Specifically, the present invention relates to a nozzle mount for a hydraulic excavation device for use in soft drilling applications.
Existing buried gas, electric, water, telephone, and sewer utility lines are in constant need of repair and replacement. Laying new service lines in areas where existing lines are already buried is complicated by the risk of damaging existing lines during excavation.
For instance, when excavation work must be done in a right-of-way containing a fiber optic cable, it is often desirable to accurately determine the location of the fiber optic cable so that the excavator can avoid damaging it. However, the exact location of a cable buried between manholes can be difficult to determine. Earth movement and settling may have shifted the cable from its original location and render it difficult to locate. Furthermore, the absence of ferrous metals and current-carrying conductive wires from a fiber optic cable can preclude or at least minimize the suitability of magnetic and current-detecting devices. Thus, locating buried fiber optic cables often requires physically exposing them. In this manner their locations can be determined with relative precision. Between the manholes the cable right-of-way is typically xe2x80x9cpotholedxe2x80x9d by excavating at predetermined intervals to expose the buried cable. If only the cable location is desired, a large opening is generally unnecessary. Potholing may be accomplished with hand tools, machines, or both. However, since hand tools are relatively slow and equipment use is attended by a risk of cable damage, both methods have their drawbacks.
The use of mechanical excavation devices such as backhoes, augers, or even shovels threaten to damage undetected buried lines. xe2x80x9cSoftxe2x80x9d excavation devices use liquid or pneumatic cutting actions in order to prevent damage to underground lines. Devices known in the field are shown in U.S. Pat. Nos. 5,887,667 and 5,860,232. These references disclose an alternative method of excavating each of which has advantages and disadvantages. Typically, these types of excavation, as compared to more conventional methods of mechanical excavation, require higher energy use per volume of material excavated, and may be slower than the conventional excavation. Some devices such as the device shown in U.S. Pat. No. 5,291,957 to Curlett include fluid excavation with mechanical drilling. To the extent that they rely on mechanical means for cutting, grinding or breaking up the soil, such devices still threaten to damage buried objects. There is significant need for improved soft excavation devices that will not damage existing underground lines during use.
One aspect of the present invention is directed to a nozzle mount assembly for use in soft drilling employing liquid jet nozzles. The assembly includes a straight vacuum tube of electrically nonconductive material, having proximal and distal ends, and a plurality of nozzle ports disposed around the vacuum tube. The vacuum tube defines an air relief slot near its distal end.
Another aspect of the present invention relates to a wear ring disposed on the distal end of the vacuum tube.
A further aspect of the present invention relates to angling the nozzle ports such that at least one nozzle port is angled toward the inside of the vacuum tube and at least one nozzle port is angled away from the vacuum tube.
Another aspect of the present invention relates to configuring a nozzle port to be angled to direct fluid through the air relief slot.
Yet another aspect of the present invention relates to a manifold for use with a vacuum tube in soft excavation. The manifold is configured to be disposed around the vacuum tube. The manifold includes a plurality of nozzle ports, at least one of which is inwardly angled and at least one of which is outwardly angled. The manifold further defines an air trough separating two of the nozzle ports.